Two-cycle engine.



J. J. MGGUIRB. TWO CYCLE ENGINE. APPLICATION FILED JUNE 9,1910.

Patented Jan. 9, 1912.

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JAMES J, MCGUIBE, 0F ST. LOUIS, MISSOURI.

Two-CYCLE ENGINE.

Specification of Letters Patent.

Patented Jan. 9, 1912].

Application led June 9, 1910. Serial No. 565,956.

To all whom "it may concern:

Be it known that I, JAMES J.' McGmRn,

a citizen of the United States, residing at St. Louis, Missouri, haveinvented a certain 4new and useful Improvement in Two-Cycle Engines, ofwhich the following is a full, clear, and exact description, such aswill enable others skilled in the-art to which it appertains to make anduse the same.

This invention relates to internal combustionengines, and particularlyto twocycle engines.

It is well-known that in the ordinary two-cycle engine the combustiblegas or mixture is introduced into the crank case of the engine before itis admitted to the cylinder so that it will be partially compressed onthe power stroke of the piston andforced out of the crank case into thecylinder. In view of the fact that the power stroke of the piston isutilized to force thegas from the crank case into the cylinder, it isnecessary to have the inlet port of the cylinder open at the same timethe exhaust port of the cylinder is open. Consequently, some of thecombustible gas which is forced into the cylinder on the power stroke ofthe piston mingles with the burned gases and escapes through the exhaustport before the piston returns `or starts on its compression stroke.This, of course, is a very objectionable feature as a great deal of fuelis wasted and some of the burned gases remain in the cylinder, andanother objectionable feature of such engines is that the gas in thecrank case becomes dirty and also escapes from the crank case if thebearings of the crank shaft are not perfectly tight.

One object of my invention is to provide a two-cycle engine which doesnot have the objectionable features above referred to, and to this end Ihave designed a twocycle engine in which the combustible gas or mixtureisforced directly into the cylinder under pressure instead of beingfirst admitted to the crank case and then forced into the cylinder,thereby permitting the inlet port of the cylinder to be closed when theexhaust port is open and also preventing the gas from coming in contactwith dirty lubricating oil orother foreign matter before it enters thecylinder.

Another object of my invention is to provide a two-cycle engine which isso designed that the cylinder will be thoroughly scavenged at each cycleof operations so as to drive out all of the burned gases, this beingaccomplished by means of an air valve which opens sutomatlcally andadniits air into the cylinl ,Other objects and desirable features of myinvention will be hereinafter pointed out.

Figure l of the drawings is a verticalV sectional view of afour-cylinder two-cycle engine constructed 'in accordance with myinvention; Fig. 2 is a front elevational view of the engine shown inFig. l; and Fig. 3 is a detail vertical4 sectional view illustrating aslightly modified form of my invention.

While I have herein shown my invention embodied in a four-cylinderengine, I wish it to be clearly understood that my invention` isapplicable to internal combustion engines provided with one cylinder ora plurality of cylinders.

Referring to the drawings which illustrate a fourcylinder engine, Adesignates the cylinders of the engine, and B designates the pistons insaid cylinders which are connected by means of links l to Vcrank arms 2on the crank shaft 3. Each cylinder is provided with an ignition device4 and an inlet port 5 in which an inlet valve 6 is seated, said valvebeing mechanically operated and so timed that it is opened when theexhaust port 7 of the cylinder is closed. The combustible gas or mixtureis forced into the cylinder under pressure by means of a blower, pump orother suitable device C which is arranged in a supply pipe 8 that leadsfrom the carbureter 9 to a gas manifold lO with which the inlet ports 5of the various cylinders communicate.

In the construction shown in Fig. Leonduits 1l lead from the gasmanifold to gas inlet chambers l2 in which the inlet valves 6 areseated, but I wish it to be clearly understood thatit is immaterial, sofar as my broad idea is concerned, how the gas is conducted from thesource of supply to the cylinders or what particular means is used forpartially compressing the gas and forcing it in they cylinders.Furthermore, while I have illustrated the pump or blower C as beingdriven by a belt 13 that passes around the pulley on the cam shaft 14,it will be obvious that various other means could be employed fordriving the blower or device used for partially compressing the gas andforcing it into the cylinder.

The means for scavenging the cylinder so as to drive out the burnedgases consists priat a comparatively slow speed and which have only afew cylinders that exhaust into the open atmosphere or into a muler oflarge enough dimensions to overcome any tendency of back pressure, thisvacuum pump or suction device can be omitted and the partial vacuum thatis produced in the cylinder on the power strokel of the piston can berelied upon to cause the automatic air inlet valve 4to open.

In Figs. 1 and 2 I have illustrated an engine that is provided with avacuum pump or device for creating a partial vacuum in the cylinders,and in Fig. 3 I have illustrated an engine in which the partial vacuumpro duced in the cylinder by the power stroke of the Apiston is reliedupon to cause the automatic air'inlet valve to open. In the form of myinvention shown in Fig. 1 an inwardly opening automatic air valve D isarranged in the side wall of the cylinder at a point between the exhaustport 7 and the upper end of the cylinder, and an auxiliary exhaust valve15, shown in dotted lines in Fig. 2, is arranged adjacent the upper endof the cylinder in an auxiliary exhaust port which communicates with anauxiliary exhaust manifold 16, said manifold being connected by conduits17 with auxiliary exhaust chambers 18 of substantially the sameconstruction as the air inlet chambers 12, previously described. Eachcylinder ofthe engine is provided with an air inlet chamber 12 and anauxiliary exhaust chamber 18 which is located at one side of theinletchamber 12, said chambers being separated from each other by meansof a partition. A partial vacuum is created in this auxiliary exhaustmanifold 16 by means of a vacuum pump or other suitable device 19 thatcommunicates with a pipe 20 which leads to said manifold, said pumpbeing driven by means of a belt 21 which passes over a pulley on the camshaft 14 of the engine.

The inlet valve 6 and the auxiliary exhaust valve 15 of each cylinderare of substantially the same construction, and said valves are providedwith stems 6 and 15a that pass downwardly through stuffing boxes 6b, 15band stationary guide lugs 22. Said valve stems are provided at theirlower ends with inverted cup-shaped steel caps 23 for holding the usualpads or bumpers 24 against which the upper ends of the valvelifters 25bear and said valve-lifters are slidingly mounted in cages 26 that aresupported by the top wall of the crank case E of the engine and integrallugs 27 on the front wall of said crank case, as shown in Fig. l. Thecam shaft 14 is provided with a set of cams 28 which actuateA thevalve-lifters 25 with which the auxiliary exhaust valves l5 coperate,and also a separate and .distinct set of cams 29 which actuate thevalve-lifters 25 with which the gas inlet valves 6 coperate, the set ofcams 28 being' so arranged that the auxiliary exhaust valves open in ad.

vance of the gasinlet valves. Coiledexpansion springs 25a are mounted onthe stems of the inlet valves and auxiliary exhaust valves between theguide lugs 22 and the steel caps 23 on the lower ends of said valvestems so as to close said valves and hold them seated. A by-pass 30 ispreferably arranged around the blower C, and a relief valve 31 isarranged in said by-pass so as to permit the gas which has beencompressed to travel back through the by-pass 1n case the pressure inthe gas manifold 10 exceeds a certain degree, said relief val-ve 31being so designed that it will open automatically lwhen the gas in themanifold 10 or in the upper part of the by-pass reaches a certainpressure. A throttle valve 32 is arranged between `the carbureter 9 andthe blower C so as to control the supply of combustible gas to theengine, and a check valve 33 is arranged between said throttle valve andthe carbureter so as to prevent the gas which circulates through theby-pass from returning to the carbureter.

On the power stroke of the engine, namely,

when the pistons move in the direction 1ndicated by the arrow :u in Fig.1, the gas inlet valves 6 and auxiliary exhaust valves 15 will remainclosed and when the pistons uncover the main exhaust ports 7 most of theburned gases in the cylinders will escape through said main exhaustports. On the return stroke or compression stroke the auxiliary exhaustvalves 15 open after the pistons have closed the main exhaust port 7,thereby establishin communication between the cylinders am? theauxiliary exhaust manifold 16. The suction which is created in the upperends of the cylinders when the auxiliary exhaust valves open causes theair inlet valves D to open automatically and thus permit blasts of airto rush through the cylinders and scavenge same or force the burnedgases into the auxiliary exhaust manifold 16 from` which said burnedgases escape through the conduit 20. As soon as the auxiliary exhaustvalves close the gas inlet valves 6 open and thus permit the partiallycompressed gas in the gas manifold 10 to flow into the cylinders, thecharge that is admitted to each cylinder being further compressed by thecompression strokes of the pistons. The explosion of the charges in thecylinders causes the pistons to move in the opposite direction, and whenthe pistons uncover the main exhaust ports 7 most of the burned gaseswill escape from the cylinders. While it is desirable to use a vacuumpump or other suction device for creating a partial vacuum in thecylinders of englnes which have a large number of cylinders and travelat a high speed, still with other types of engines, namely, those whichhave onl a few cylinders and travel at a slow-spec a suction device orexhauster is not absolutely necessary to the successful operation of theengine.

In Fig. 3 Ihave illustrated a port-ion of an engine of the type lastreferred to, said engine being provided with means of substantially thesame construction shown in Fig. 1 for partially compressing the gas andforcing itinto the cylinder, and also provided with an inwardly openingautomatic air valve D which is arranged at the upper end of the cylinderpreferably in the head 0f the cylinder. In such a structure the burnedgases escape freely from the exhaust portv 7 'l when the pistoncompletes its ower stroke, and as said gases coolv rapidly a partialvacuum will be created in the cylinder which causes the air inlet valveD to open automat cally and thus permit a char e of fresh air to rushthrough the cylinder an scavenge same or force out any burned gaseswhich remain therein, said air inlet valve returning automatically toits closed position as soon as the piston covers the exhaust port 7 a onits compression stroke.

In addition to the desirable features above set forth, my engine alsocomprises other features which make it a decided im rovement on thetwo-.cycle engines hereto ore in use. One of these desirable featuresconsists of pistons and cylinders which are so designed thatcomparatively long crank arms 2 can be used on the crank shaft and thusobtain a long stroke, the cylinders being 'provided at their lower endswith grooves 34 and the pistons being provided at their lower ends withslots 35 which provide a clearance for the piston-operating links 1 whenthe crank arms are midway their dead center positions.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. A two-cycle internal combustion engine provided with a pluralit ofcylinders, gas inlet valves for said cy inders, means for openin saidvalves at each cycle of operations w en the exhaust orts of thecylinders are closed, a gas manifo d that communicates with the inletports of said cylinders, means for partially compressin combustible gasand supplying it to sai manifold, means for maintaining av certainpressure in said manifold when the engine is in operation, an auxiliaryexhaust manifold, auxiliary exhaust valves which open and close at eachcycleof operations, and means for creating a partial vacuum in saidexhaust manifold.

2. In a two-cycle internal combustion engine, a gas manifold, acompressor arranged between said manifold and the source of supply forartially compressin the gas that is intro uced into said mani old, abypass arranged around said compressor, and a valve in said'by-pass.

3. vIn a two-cycle internal combustion engine, a gas manifold, acompressor arranged between said manifold and the source of supply forpartially compressin the gas that is introduced into said mani old, abypass arranged around said compressor, a relief valve in said by-passthat opens automatically when the pressure in the manifold exceeds acertain degree, and a check valve arranged between said by-pass and thesource of supply.

In testimony whereof I hereunto affix my signature in the presence oftwo witnesses, this sixth day of June, 1910. l

JAMES J. MCGUIRE.

Witnesses:

WELLS L. CHURCH, GEORGE BAKEWELL.

